1. Field of the Invention
The present invention relates to a wrong insertion preventing mechanism, particularly relates to a mechanism for preventing a wrong connector of a printed wiring board from being inserted into a connector mounted on a mother board in a cabinet.
2. Description of the Related Prior Art
Recently, various electronic equipments have configuration that plural plug-in units are housed on a shelf also called a subrack (hereinafter called a shelf). Such electronic equipment is provided with proper functions when a plug-in unit is installed in a right position on a shelf. In case a plug-in unit is not set in a right position, electronic equipment cannot acquire required functions and in addition, the plug-in unit may be broken. A plug-in unit includes a printed wiring board, a connector mounted on the board and a lever (an ejector) operated when the board is detached/attached from/to a connector of a shelf. Normally, of connected connectors, one receptacle connector is mounted on a mother board on a shelf and the other plug connector is installed in a plug-in unit. To prevent connectors from being wrongly inserted, a wrong insertion preventing component is installed in the vicinity of the connector. For example, a wrong insertion preventing component having the L-type section is installed in the vicinity of a receptacle connector and a wrong insertion preventing component having the L-type section is also installed in the vicinity of a plug connector corresponding to the component. The respective L-type wrong insertion preventing components of a receptacle connector and a plug connector to be electrically connected are installed so that its concave portion and its convex portion are fitted when the connectors approach. Also, the respective L-type wrong insertion preventing components of a receptacle connector and a plug connector to be not electrically connected are installed so that its convex portion and its concave portion mutually bump when the connectors approach. When a plug-in unit is inserted in a right position of a shelf, two L-type wrong insertion preventing components do not bump and therefore, a right plug connector is connected to a receptacle connector. When a plug-in unit is inserted in a wrong position of a shelf, the convex portions of two L-type wrong insertion preventing components mutually bump and the plug-in unit is not inserted moreover. Therefore, a receptacle connector is not connected to a wrong plug connector.
However, the conventional type wrong insertion preventing mechanism described above has the following problems. As electronic equipment is recently provided with many functions and becomes complex, the number of pins of a connector of a printed wiring board is greatly increased. Therefore, large force is required to connect connectors. Force required for insertion per pin of a certain type of connector is approximately 500 mN (millinewton) for example and in the case of a plug connector having 1000 pins, approximately 500 N is required for connecting the connector. Therefore, a conventional type plug-in unit is provided with an ejector that connects connectors. Normally, when wrong insertion preventing components installed in the vicinity of each connector bump, an operator already starts operation for connecting connectors by an ejector and it is difficult to detect resistance force caused when the wrong insertion preventing components bump. Therefore, the wrong insertion preventing components are broken or connectors are connected by mistake. For another problem, the combination of wrong insertion preventing components is limited. That is, as the combination in the number, the installed position and the orientation of the L-type wrong insertion preventing components described above is limited, the increase of the number of plug-in units installed on a shelf cannot be met. Also, a connector in which a wrong insertion preventing component cannot be set is used in large numbers.
Therefore, the object of the invention is to provide a wrong insertion preventing mechanism which can detect wrong insertion before a connector on a shelf and a connector of a plug-in unit are touched, can sufficiently correspond to the increase of the number of plug-in units and further, can be applied to many types of connectors.
To achieve the object, the wrong insertion preventing mechanism is provided with a guide pin holder attached to a board having a connector, a guide pin held in the guide pin holder so that the guide pin can be detached and a guide plate having a through hole which is made at the opening of the shelf having the connector and which a specific guide pin can pierce.
In a concrete example of the wrong insertion preventing mechanism, the guide plate has plural through holes and each specific guide pin pierces each through hole. In another concrete example, a projection is formed at the end of the guide pin in a radial direction of the guide pin, the projection is formed in any of predetermined plural positions in the guide pin holder and plural through holes formed in the guide plate respectively have a shape corresponding to a specific position in which the projection of the guide pin is formed. The wrong insertion preventing mechanism can be provided with a lever attached to the board so that the lever can be turned, the lever can connect the connector of the board to the connector on the shelf by being turned and pressing the guide plate and can pull out the connector of the board from the connector on the shelf by being turned and pressing the guide plate. In the wrong insertion preventing mechanism, connectors to be connected can be securely connected.